Strings of decorative lights are used for adornment of Christmas trees and for other holiday functions. Certain types of light strings are wired in series. Therefore, when one bulb burns out, the entire string of lights goes out. It is then a matter of considerable effort and aggravation to determine which light bulb out of many is bad. Presently, one must unplug the string, remove each bulb, one at a time, and either test it or replace it with a bulb known to be good. After each replacement, the entire string must be plugged in again to see if the problem has been corrected. The light strings are mass produced out of the least expensive materials possible, so the very act of removing even a good bulb may damage it or its socket.
Prior developments in this field may be generally illustrated by reference to the following patents:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,725,780 R. Olin Apr. 03, 1973 4,943,752 P. Todd et al. Jul. 24, 1990 2,501,548 A. Street Mar. 21, 1950 2,155,778 E. Stratton Apr. 25, 1939 3,760,266 G. Ocasio Sep. 18, 1973 2,746,011 P. Carson May 15, 1952 2,756,384 J. Meyer Jul. 24, 1956 4,617,519 E. Rosenthal Oct. 14, 1986 1,411,430 J. Graves Apr. 04, 1922 ______________________________________
U.S. Pat. No. 3,725,780 teaches a portable battery-powered holiday light bulb tester designed to handle two-pronged miniature bulbs.
U.S. Pat. No. 4,943,752 teaches a portable holiday light tester powered by a piezoelectric crystal.
U.S. Pat. Nos. 2,501,548 and 2,155,778 show battery-powered light bulb testers.
U.S. Pat. Nos. 3,760,266 and 2,746,011 teach holiday light testers that plug into the house circuit.
The rest of the patents are representative of what is in the art.
None of the patents show the use of precisely-spaced double prongs which fit into the bottom wire-exit apertures of standard holiday light sockets.